1. Field of the Invention
The present invention relates to a method for room temperature chemical deposition on a flexible polymer and an apparatus therefor.
2. Description of the Related Art
As rapid operation and small-size trend of micro-systems, electronic equipments and apparatuses also seek high speed and small size. Also, due to the increase of the need of such equipments and apparatuses, the miniaturization are further required. The apparatuses should be manufactured in a smaller size while the whole functions remain or are improved. Therefore, concerns about cheap and reliable compact packages are increased.
In a general electric circuit, 80% of the electronic components are passive components (capacitor, resistance and inductance) and occupy 50% of the print-wiring-board area. Therefore, it has been attempted to embed the passive components on PCB (printed circuit boards) or compact the package using LTCC (low temperature co-fired ceramics).
By embedding of the passive components, in addition to the miniaturization, the signal path is very increased and consequently, noise is reduced, thereby improving performance of electronic products, particularly high frequency apparatus.
As an embedding capacitor processed at a temperature where the PCB can stand, Bi2O3—ZnO—Nb2O5(BZN) thin film has been reported by Park et al.
Organic thin film transistors (OTFT) are spot-lighted in application fields requiring structural flexibility, applicability at a large area, low temperature processibility and low expense. The OTFT mounted on low voltage operating/high output polymer substrate is expected to enable us to develop various techniques including low price digital logic apparatus, electronic book, electronic paper, wearable electronic products and large size flexible display.
Also, the electronic apparatuses are combined and miniaturized by using thin film technique suitable at a temperature near room temperature and miniaturized by providing a dielectric thin film having a high dielectric constant. The physical vapor deposition (PVD) technique such as sputtering and pulse laser deposition allows deposition without heating of the substrate though the film is not crystallized.
Generally, the hetero nucleation and growth in the film deposition by CVD are accomplished by adsorption, chemical reaction, desorption on the substrate surface at a high temperature. Therefore, the substrate should be heated to decompose precursors near the surface.
Meanwhile, in case of the flexible polymer substrate such as polyimide film which can realize small-size and light weight is readily applied to small size electronic equipments including mobile phone, PDA, notebook and the like and is well used in printer, HDD and the like because of practicability of three-dimensional wiring and excellent flexibility. Also, unlike the conventional silicone based substrates, it can be advantageously produced continuously by the roll-to-roll fashion. However, in spite of such advantages, it has a difficulty in handling due to low mechanic strength and a limit in production process due to high contraction rate and weakness to heat (limit temperature resistance of about 200° C.). Particularly, the flexible polymer substrate had a difficulty in application to the conventional chemical vapor deposition, in which the substrate is heated over the critical temperature to decompose precursors. Also, the atomic layer deposition (ALD) which has recently developed for preparation of ultra thin film cannot be operated at a temperature under 200° C. which is temperature limit of the thin film on the flexible substrate.
In order to overcome the limits in treatment temperature, it is possible to reduce the temperature of the substrate for deposition of thin film by applying the plasma-enhanced CVD method. However, there may be defects such as poor conformal deposition or damage in the substrate by plasma.
Therefore, it is demanded to develop a novel room temperature CVD technique on a flexible polymer substrate which meets the small size and light weight trend of electronic parts and products and is readily performed.